On Tue, 2007-03-06 at 07:24 +0000, Peter P. wrote:
> Wouter van Ooijen <wouter <at> voti.nl> writes:
> 
> > If I understand you right: You used a chip outside its specs and it
> > worked. You use the newer chip this way and it fails. And you are
> > surprised?
> 
> That is not what I was saying. What I was saying was, that the spec is lying or
> wrong. The actual permitted Vclamp is probably Vdd+0.3V/Vss-0.3V as opposed to
> the stated 0.6V. 

Correct me if I'm wrong, but the specs you're looking at are in the
absolute maximum section of the datasheet. Those ratings simply state
you won't KILL the part by doing what the ratings describe, they say
NOTHING of whether the part will function or not.

For normal functions I can't see why you'd expect going below GND would
be a good idea.

The older chips worked? So what, you were out of operating spec with
them and got lucky, now it's biting you. I've been there myself. 

I have a board with a voltage supply for some DRAM. Everything worked
fine, until a recent run of the boards resulted in no Vdd for the DRAMs.
Comparing the working board with the non working boards only revealed
one difference: the regulator chip was a rev. C on the new boards, and
was rev. B on the old boards. Turns out I had strapped the chips out of
spec, the old chips were fine with that, the new chips were not. Lesson
learned, don't go out of spec.

TTYL

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